Servo writing operations employing arm assemblies and laser interferometers are known in the art. The writing operation is accomplished by laser positioning of the servo transducer head with the servo data surface to define precise servo tracks. Precise alignment during the servo track writing operation is mandatory.
Prior attempts to accomplish precise alignment have included the use of granite blocks as a base for servo writing equipment to establish rigidity and freedom from vibrational perturbations. Clipping devices have been employed to attach the servo writing devices to the arm assemblies. Detent mechanisms have also been used to provide continuous alignment throughout the servo writing operation.
The use of granite blocks as a base for servo writing equipment provides some mechanical rigidity; however, complete rigidity has not been realized and precise alignment is not accomplished merely by use of granite blocks bases for servo writers.
Prior clipping devices for removably clipping tools, such as retroreflectors, onto the servo transducer arm assembly have failed both to provide sufficient mechanical rigidity and positive alignment. Servo writing operations have been expensive because the inadequate clipping devices required constant realignment thereby causing the writing operations to be slow and cumbersome.
Detent mechanisms employed to accomplish alignment were often complex; therefore, they were often expensive to produce and slow to operate. One such detent mechanism, discussed in the Applequist U.S. Pat. No. 3,875,589, for use with disk packs, is believed by applicant to be unsuitable for use with robotics because of its complexity.
Another method for alignment discussed in the present assignee's Moon U.S. Pat. No. 4,669,004, used a step motor to rotate a lead screw that clamped onto a lever with a pin that physically engaged the arm assembly. The lead screw follower method failed to provide alignment as precise as that achieved by the use of the laser interferometer with the result that fewer servo sectors and data tracks were written on a given data storage surface.
As can be seen from the above summary of the prior art, an unsolved need exists for rapid, low cost, positive alignment coupled with mechanical rigidity for servo writing devices attached to servo transducer heads for writing operations on a rigid disk drive with a plurality of disks.